Membrane Stabilization of Poly(ethylene glycol)-b-polypeptide-g-trehalose Assists Cryopreservation of Red Blood Cells

As alternative cryoprotectants of conventional organic glycerol, biocompatible synthetic glycopeptides that can assist cryopreservation of red blood cells (RBCs) are proposed in this study. A series of glycopeptides are synthesized via ring-opening polymerization of N-carboxyanhydrides of lysine, aspartic acid, and phenylalanine initiated by poly(ethylene glycol)-NH2 and followed by chemical tethering carboxylated trehalose to the pendant amino moieties. The synthetic glycopeptides demonstrate distinguished features of low cytotoxicity, low hemolysis, and cell membrane stabilization. The specifically designed glycopeptides enhance cryosurvival recovery of sheep RBCs up to 87.3 ± 0.3% at pH 6.0 and 86.5 ± 0.3% at pH 7.4 together with trehalose during cryopreservation. The synergistic cryopreservation of RBCs is achieved via membrane stabilization of the glycopeptide and ice recrystallization inhibition of trehalose during freezing and thawing. Molecular dynamics simulation indicates that the glycopeptides enhance membrane stabilization at -196 °C by tuning water diffusion. This work provides a potential option of highly efficient and glycerol-free RBC cryopreservation by combination of synthetic glycopeptides and trehalose, which would inspire design and utilization of different mechanisms for the effective cryopreservation of cells or tissues.